Russia's damaged wheat: a glimpse of the future?

Steve Baragona in Voice of America: As Russian wheat withers under a record-breaking heat wave, driving up grain prices on global commodity markets, a new study shows rice production, too, has suffered in recent decades from rising temperatures. Experts say it may be the latest warning of how climate change in some key farming regions could threaten world food supplies.

In the new study in the Proceedings of the National Academy of Sciences, researchers examined six years of data from 227 farms in six major rice-producing countries in Asia. They looked at how rice production varied depending on the weather, and extrapolated those effects over the past quarter-century. They found that "higher nighttime temperatures lead to lower yield," says lead author Jarrod Welch at the University of California, San Diego (UCSD).

In the southern U.S. state of Louisiana, the nation's third-largest producer of rice, hot nighttime temperatures have made the plants susceptible to a bacterial disease. Rice farmer Clarence Berken says yields are off by 25 to 30 percent in some of his fields. "Especially in a year like this year, when [the price] for our crop is about half of what it was two years ago, and input costs have basically stayed the same," he says, "it's really something that's worrisome."

There may be more to worry about in the future for Berken and rice farmers around the world, because nighttime temperatures are predicted to rise faster with climate change than daytime temperatures. Welch says the negative impact on productivity could make rice more expensive in the future.

"The numbers of people that depend on rice are astronomical," he says. "Something like 3 billion people eat rice every day. Six hundred million or so depend on it as their staple food. And those 600 million are among the world's poorest billion."

Rice consumers aren't the only ones put at risk by rising temperatures. Last fall, another major study looking at U.S. maize, soybean and cotton production showed that yields go down for each day a crop is exposed to temperatures above a certain threshold. Depending on how fast the climate warms this century, the study predicted crop yield declines from 30 to 80 percent….

Japanese symbol for rice